Control system and method and control device therefor

ABSTRACT

A control system having a control unit provided with a single thermostatically operated control device for operatively interconnecting a heater to a source of energy when the output temperature effect of the heater is below a predetermined setting of a selector of the control unit and to disconnect the heater from the source of energy when the output temperature effect of the heater is above the predetermined setting of the selector, the single thermostatically operated control device also operating an indicating light to indicate that the output temperature effect of the heater is still above a certain value only when the selector of the control unit is in an &#34;off&#34; setting thereof. The selector of the control unit also operates a pilot light to indicate that the selector is set in an &#34;on&#34; setting thereof.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part application of its copendingparent application, Ser. No. 795,403, filed May 9, 1977 now U.S. Pat.No. 4,110,601, which, in turn, is a continuation application of itscopending parent application, Ser. No. 550,456, filed Feb. 18, 1975, andnow abandoned in favor of its said copending continuation application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improved control system for a heatingelement or the like and to a method of making such a control system aswell as to a control device for such a system or the like.

2. Prior Art Statement

It is known to provide a control system for a heater means wherein anindicator means will be in an "on" condition to indicate that the outputheating effect of the heating means is above a certain value even thoughthe selector means for the control system is disposed in the "off"setting thereof whereby such indicating means will provide a warningthat the heating means is at an unsafe temperature, such as being abovea safe-to-touch temperature.

For example see the following two items:

(1) U.S. Pat. No. 3,612,826--Deaton.

(2) U.S. Pat. No. 2,593,812--Turner.

The above patent to Deaton appears to have one temperature responsivedevice for operating the indicating means and other temperatureresponsive means separate from the one temperature responsive device foroperating the heater means.

The above patent to Turner appears to have a temperature responsivedevice operating an indicating lamp to indicate that the outputtemperature effect of the heating means controlled by the temperatureresponsive device is at a value higher than the setting of the selectormeans thereof for any setting of the selector means.

SUMMARY OF THE INVENTION

It is a feature of this invention to provide a control system for aheater means wherein a single temperature responsive device controlsboth the operation of the heater means and the operation of theindicator means that indicates that the output temperature effect of theheater means is still above a certain value even though the selectormeans for the control system is set in an "off" setting thereof.

In particular, one embodiment of this invention provides a controlsystem having a source of energy means, heater means, indicator means,and thermostatically operated control means having selector means forsetting the control means in a heater means non-temperature producing"off" setting or in a heater means temperature producing "on" setting.The control means has a single temperature responsive device operativelyinterconnected to the means of the system to interconnect the heatermeans to the energy means when the output temperature effect of theheater means is below a predetermined "on" setting of the control meansand to disconnect the heater means from the energy means when the outputtemperature effect of the heater means is above the predetermined "on"setting of the control means, the single temperature responsive deviceof the control means operating the indicating means to indicate that theoutput temperature effect of the heater means is above a certain valueonly when the control means is in the "off" setting thereof. The controlmeans has switch means continuously operating the indicating meansindependently of the temperature responsive device and regardless of theoutput temperature effect of the heater means to indicate that theselector means is set in the "on" setting thereof only when the selectormeans is set in the "on" setting thereof.

Accordingly, it is an object of this invention to provide an improvedcontrol system having one or more of the novel features of thisinvention as set forth above or hereinafter shown or described.

Another object of this invention is to provide a method of making such acontrol system, the method of this invention having one or more of thenovel features of this invention as set forth above or hereinafter shownor described.

Another object of this invention is to provide an improved controlsystem for such a system or the like.

Other objects, uses and advantages of this invention are apparent from areading of this description, which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating the control system of thisinvention when set in an "off" condition thereof and the outputtemperature effect of the heating means is below a certain valuethereof.

FIG. 2 is a view similar to FIG. 1 and illustrates the control systemwhen set in an "off" condition thereof and the output temperature effectof the heating means is above a certain value thereof.

FIG. 3 is a view similar to FIG. 1 and illustrates the control systemwhen in an "on" condition thereof and a demand is being made foroperation of the heating means thereof.

FIG. 4 is a view similar to FIG. 3 and illustrates the control system inan "on" condition thereof and when a demand for operation of the heatingmeans is not being made.

FIG. 5 is a view of the control device utilized in the system of FIGS.1-4 and with the cover thereof removed.

FIG. 6 is a cross-sectional view taken on line 6--6 of FIG. 5.

FIG. 7 is a cross-sectional view taken on line 7--7 of FIG. 5.

FIG. 8 is a schematic view of another control system of this inventionwith the control system of FIG. 8 being disposed in an "off" conditionthereof and the output temperature effect of the heating means beingbelow a certain value.

FIG. 9 is a view similar to FIG. 8 and illustrates the control systemwhen in its "off" condition and the output temperature effect of theheating means being above a certain value.

FIG. 10 is a view similar to FIG. 8 and illustrates the control systemset in an "on" condition thereof and with a demand being made for theheating means to be operated.

FIG. 11 is a view similar to FIG. 8 and illustrates the control systemin an "on" condition thereof and when a demand is not being made thatthe heating means be in an operating condition thereof.

FIG. 12 is a schematic view illustrating another control system of thisinvention with the control system of FIG. 12 being disposed in an "off"condition thereof and the output temperature effect of the heating meansis below a certain value thereof.

FIG. 13 is a view similar to FIG. 12 and illustrates the control systemwhen set in an "off" condition thereof and the output temperature effectof the heating means is above a certain value thereof.

FIG. 14 is a view similar to FIG. 12 and illustrates the control systemwhen in an "on" condition thereof and a demand is being made foroperation of the heating means thereof.

FIG. 15 is a view similar to FIG. 12 and illustrates the control systemin an "on" condition thereof and when a demand for operation of theheating means is not being made.

FIG. 16 is a view of the control device utilized in the system of FIGS.1-4 and with the cover thereof removed.

FIG. 17 is a cross-sectional view taken on line 17--17 of FIG. 16.

FIG. 18 is a cross-sectional view taken on line 18--18 of FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While various features of this invention are hereinafter described andillustrated as being particularly adapted to provide a control systemfor an electrical heating means, it is to be understood that the variousfeatures of this invention can be utilized singly or in any combinationthereof to provide a control system for other types of heating means asdesired.

Therefore, this invention is not to be limited to only the embodimentsillustrated in the drawings, because the drawings are merely utilized toillustrate one of the wide variety of uses of this invention.

Referring now to FIGS. 1-4, one control system of this invention isgenerally indicated by the reference numeral 20 and comprises a powersource represented by L1, interconnected by a lead 21 to a terminal 22of a temperature responsive control device that is generally indicatedby the reference numeral 23 and comprises a housing means 24 asillustrated schematically in FIGS. 1-4 and in detail in FIGS. 5-7.

The control system 20 includes an electrical heater element 25 adaptedto have one side 26 thereof interconnected by a lead 27 to ground whilethe other side 28 thereof is interconnected by a lead 29 to anotherterminal 30 of the control device 23.

The system 20 includes an indicating device 31 which in the embodimentillustrated in the drawings comprises a light bulb having one side 32thereof interconnected by a lead 33 to ground and the other side 34thereof interconnected by a lead 35 to another terminal 36 of thecontrol device 23.

The control means or device 23 includes three electrical switchesrespectively being generally indicated by the reference numerals 37, 38and 39 in FIGS. 1-4.

The electrical switch 37 includes a fixed contact 38' and a movablecontact 39' being carried on a switch blade 40 that is controlled by cammeans (not shown) of a selector shaft or means 41 of the control device23 so that when the shaft 41 is disposed in the "off" position of FIGS.1 and 2, the switch blade 40 is positively held in such a position thatthe movable contact 39' is maintained out of contact with the fixedcontact 38'. However, when the control shaft 41 is set in any "on"position thereof, the cam means of the shaft 41 positively maintains theswitch blade 40 to the left so that the contact 39' is maintained incontact with the fixed contact 38' as illustrated in FIGS. 3 and 4.

The switch blade 40 of the first switch 37 is interconnected by suitableelectrically conductive means 41' to switch blades 42 and 43respectively of the switches 38 and 39 whereby the switch blades 42 and43 comprise movable contacts 44 and 45 of the switches 38 and 39 whichrespectively have fixed contacts 46 and 47' for cooperating therewith.

The switch blade 43 of the switch 39 carries a threaded adjusting member47 which is adapted to have its free end 48 abut against the switchblade 42 as illustrated in the drawings as the natural bias of the blade43 is toward the blade 42.

A power element 49 has a movable wall 50 provided with an abutment 51for engaging against the switch blade 42 as illustrated in the drawings,the movable wall 50 being adapted to move to the right when atemperature sensing bulb (not shown) senses an increase in temperatureand is adapted to cause the movable wall 50 to collapse to the left whenthe sensed temperature decreases in a manner well known in the art. Suchtemperature sensing bulb is so constructed and arranged that the samesenses the output temperature effect of the heating means 25 for apurpose hereinafter described whereby the power element 49 istemperature responsive.

The power element 49 is interconnected to the control shaft 41 in amanner well known in the art so that when the control shaft 41 is movedto the "off" position illustrated in FIGS. 1 and 2, the power element 49is moved to a position to maintain the switch blade 42 in an opencondition relative to the fixed contact 46 regardless of the temperaturebeing sensed by the power element 49 and the adjusting member 47 is soconstructed and arranged that when the temperature being sensed by thepower element 49 is below a certain value, such as 160° F. or the like,the switch blade 43 is also held out of contact with the fixed contact47', as illustrated in FIG. 1. However, should the control shaft 41 bedisposed in its "off" position and the power element 49 is sensing thatthe output temperature effect of the heating means 25 is above thatcertain value, which in the above example is 160° F., the movable wall50 has expanded to the right a distance sufficient to carry the switchblades 42 and 43 to the right so that the switch blade 43 is placed intocontact with the fixed contact 47' for a purpose hereinafter described.

The conductive means 41' of the switch blades 40, 42 and 43 isinterconnected by lead means 52 to the terminal 36. The fixed contact38' of the switch 37 is interconnected by conductive means 53 to thefixed contact 47' of the switch 39 with the connector means 43 beinginterconnected to the terminal 22 by a lead 54. The fixed contact 46 ofthe switch 38 is interconnected by a lead 55 to the terminal 30.

While the various contacts and terminals of the switch construction 23schematically illustrated in FIGS. 1-4 are shown as being interconnectedby wire-like leads, it is to be understood that the same could be formedof bent metal members in the manner fully illustrated in FIGS. 5-7, asdesired. However, this invention is not to be limited to any particularconfiguration of the parts of the control device 23 as illustrated inFIGS. 5-7, as the same can be formed in any desired configuration tooperate in a manner now to be described.

With the control shaft 41 of the control device 23 disposed in the "off"condition of FIG. 1, the power element 49 is adjusted to a position sothat regardless of the temperature being sensed by the power element 49,the switch blade 42 is held in an open condition relative to the fixedcontact 46 by the power element 49 so that no electrical current can bedirected from the power source lead 21 to the heating means 25.Likewise, the shaft 41 holds the switch blade 40 in an open conditionrelative to the fixed contact 38 so that no electrical current flowingfrom the power source lead 21 can pass through the switch 37.

If the temperature being sensed by the power element 49 is below acertain value, which in the previously described example is 160° F., theposition of the switch blade 42 acting on the adjusting member 47 of theswitch blade 43 is such that it maintains the switch blade 43 in an opencondition relative to the fixed contact 47' of the switch 39 whereby noelectrical current can flow from the conducting means 53 that isinterconnected to the power source lead 21 to the terminal 36. Thus, theindicating means 31 is in its "off" condition.

However, should the output temperature effect of the heating means 25 beabove the certain value, the power element 49 has the wall 50 thereofdisposed to the right a distance sufficient to hold the switch blade 43into contact with the fixed contact 47' of the switch 39 so thatelectrical current can flow through the indicating means 31 to operatethe same to warn that the heating means 25 is still maintaining aheating condition that would be unsafe to work around the heating means25 or touch the same.

Subsequently, with the control device 23 remaining in the "off"condition, the output temperature effect of the heating means 25 willfinally fall below the certain value whereby the power element 49 willhave its movable wall 50 collapse sufficiently to the left to permit theswitch 39 to open in the manner illustrated in FIG. 1 so that theindicating light 31 will be in the "off" condition illustrated in FIG. 1and thereby indicate that the heating means 25 is at a safe temperature.

However, when an operator turns the control shaft 41 to any "on"position thereof as illustrated in FIG. 3, the control shaft 41 througha cam means thereof positively closes the fixed blade 40 against thefixed contact 39' as illustrated in FIG. 3 and maintains the same insuch closed condition whereby electrical current is adapted to flow fromthe power source lead 21, terminal 22, closed switch 37, and lead 52through the terminal 36 and indicating means 31 so that the indicatingmeans 31 will be continuously "on" as long as the control shaft 41 isset in any "on" position thereof.

Movement of the control shaft 41 to any "on" condition thereof adjuststhe position of the power element 49 so that the same will tend tomaintain the output temperature setting of the control shaft 41.

In particular, once the control shaft 41 has been set to a desiredtemperature setting thereof, such as 300° F., and the power element 49is sensing that the output temperature effect of the heating means 25 isbelow the selected temperature, the power element 49 has the wall 50thereof at such a position thereof that the switch blade 42 is incontact with the fixed contact 46 of the switch 38 so electrical currentcan flow through the closed switch 37 and the closed switch 38 to theterminal 30, and, thus, through the heating means 25 to cause the sameto operate and heat the area where the same is located.

Once the output temperature effect of the heating means 25 reaches orslightly exceeds the selected temperature setting of the shaft 41, thepower element 49 has expanded to such condition that the movable wall 50has opened the switch blade 42 relative to the fixed contact 46 toterminate the flow of current to the heating means 25 until the outputtemperature effect again falls below the selected temperature wherebythe switch 38 will close in the manner illustrated in FIG. 3.

Thus, it can be seen that the switch 38 will be cycled on and off by thepower element 49 to tend to maintain the output temperature effect ofthe heating means 25 at the temperature setting of the control shaft 41in the manner previously described.

Further, it can be seen that as long as the control shaft 41 is in any"on" condition thereof, the switch 37 is held closed and thereby theindicating lamp 31 is energized to always indicate that the controldevice is set in an "on" condition thereof.

Also, it can be seen that when the control shaft 41 is subsequentlyturned to its' "off" condition, the switch 37 is opened and the powerelement 49 positively opens the switch 38 so that no current can flowthrough the heating means 25. However, should the output temperatureeffect of the heating means 25 still be above the certain value when thecontrol shaft 41 is turned to its' "off" condition, the power element 49will maintain the switch 39 closed as illustrated in FIG. 2 so that theindicating lamp 31 will now indicate that the heating means 25 is stillat an unsafe condition, the indicating means 31 only being turned offwhen the output temperature effect of the heating means falls below thatcertain value as illustrated in FIG. 1.

Thus, the indicating means 31 of the control system 20 of this inventionprovides a dual purpose, namely indicates when the control device 23 isin "on" condition thereof and also indicates an unsafe temperaturecondition of the heating means 25 when the control device 23 is in "off"condition thereof.

While the control system 20 previously described has the control device23 provided with three electrical switches 37, 38 and 39 foraccomplishing the previously described features, another embodiment ofthis invention provides the same desired features by utilizing only twoelectrical switches in the control device thereof.

In particular, reference is now made to FIGS. 8-11 wherein anothercontrol system of this invention is generally indicated by the referencenumeral 20A and parts of the system 20A similar to the system 20previously described are indicated by like reference numerals followedby the reference "A".

As illustrated in FIGS. 8-11, the control device or means 23A of thesystem 20A includes only the electrical switches 38A and 39A as theelectrical switch 37 of the control device 23 previously described hasbeen eliminated. However, the control shaft 41A is so constructed andarranged that the same has cam means (not shown) which will maintain theswitch blade 43A into contact with the fixed contact 47'A whenever thecontrol shaft 41A is moved to any "on" position thereof as illustratedin FIGS. 10 and 11 whereby electrical current will be supplied from theterminal 22A through the closed switch 39A and terminal 36A to theindicating means 31A to continuously operate the indicating means 31A aslong as the control shaft 41A is in any "on" condition thereof. However,when the control shaft 41A is moved to its "off" position thereof, thesame has its cam means completely disconnected from the switch blade 43Aso that the switch blade 43A is under the control of the switch blade42A through the adjusting member 47A.

In particular, with the control shaft 41A set in its "off" position, thepower element 49A has been so adjusted that the same will alwaysmaintain the switch blade 42A in an open position thereof so that noelectrical current can flow from the switch blade 42A to the terminal30A that leads to the heating means 25A. However, should the temperaturebeing sensed by the power element 49A be above a certain value, themovable wall 50A of the power element 49A is disposed to the right adistance sufficient to cause the blade 42A through the adjusting member47A to hold the switch blade 43A in its closed condition against thefixed contact 47'A in the manner illustrated in FIG. 9 wherebyelectrical current is supplied through the closed switch 39A to theindicating means 31A to operate the same. Thus, the energized indicatingmeans 31A will provide a warning that the heating means 25A is stillmaintaining an output temperature effect that is unsafe or above theknown certain value thereof.

When the output temperature effect of the heating means 25A falls belowthe certain value with the shaft 41A of the control device 23A in the"off" position thereof, the movable wall 50A of the power element 49Ahas collapsed sufficiently that the switch blade 43A through its naturalbias is permitted to move away from the fixed contact 47'A so that theindicating light 31A is disconnected from the power source lead 21A inthe manner illustrated in FIG. 8.

Therefore, it can be seen that the control system 20A and the controldevice 23A operate in substantially the same manner as the controlsystem 20 and control device 23 previously described except that theswitch 37 has been eliminated and the control shaft 41A is soconstructed and arranged that the same will always close the switch 39Aand maintain the same in a closed condition thereof as long as the shaft41A is in any "on" condition thereof.

While the control systems 20 and 20A previously described each has asingle indicating means 31 and 31A for providing the dual function ofindicating that the control shaft 41 or 41A is set in an "on" conditionthereof or as a warning indicator should the control shaft 41 or 41A beset in an "off" condition thereof and the output temperature effect ofthe heater means 25 or 25A is above an unsafe value for the reasonspreviously set forth, it is to be understood that the control systems ofthis invention can utilize a separate indicating light for indicatingthat the control shaft is in a "on" condition thereof so that the otherindicating light will only be utilized to indicate an unsafe outputtemperature effect of the heater means when the control shaft is in its"off" condition.

For example, such a control system of this invention is generallyindicated by the reference numeral 20B in FIGS. 12-15 and parts thereofsimilar to the systems 20 and 20A are indicated by like referencenumerals followed by the reference letter "B".

As illustrated in FIGS. 12-15, the control system 20B includes theheater means 25B, three switches 37B, 38B and 39B, the unsafetemperature indicating lamp 31B, control shaft 41B, single temperatureresponsive device 49B and power source lead L1 and ground leads 27B and33B as previously described.

However, the side 34B of the indicating lamp 31B is interconnected bythe lead 35B to an adjustable contact 100 of the switch 39B asillustrated, the adjustable contact 100 cooperating with the switchblade 43B that is controlled by the switch blade 42B under the controlof the temperature responsive device 49B as will be apparenthereinafter.

Also, the control system 20B includes a control system "on" indicatinglamp 101 that had one side 102 thereof interconnected by a lead 103 tothe ground lead 33B while the other side 104 of the lamp 101 isinterconnected by a lead 105 to a busbar like member 106 of the controldevice 23B that is electrically interconnected to the switch blades 42Band 40B as illustrated.

The structure of the temperature responsive control device 23B of thecontrol system 20B of FIGS. 12-15 is best illustrated in FIGS. 16-18whereby it can be seen that the control device 23B of this invention canbe formed in a simple and effective manner similar to the devices 23Band 23A for the control systems 20 and 20A previously described.

The operation of the control system 20B and the control device 20B willnot be described.

When the control shaft 41B is disposed in the "on" condition of FIGS. 14and 15, the temperature responsive device 49B maintains the switch blade40B against the fixed contact 38'B of the switch means 37B in all "on"positions of the control shaft 41B so that the power source lead L1 isinterconnected through the closed switch 37B and busbar member 106 tothe indicating "on" lamp 101 and, thus, to the ground lead 33B asindicated by heavy lines in FIGS. 14 and 15 whereby the indicating "on"lamp 101 will continuously indicate that the control shaft 41B is set inan "on" position thereof.

During such "on" setting of the control shaft 41B should the temperatureresponsive device 49B sense a demand for heat output from the heatermeans 25B, the same causes the switch blade 42B to close the switch 38Bas illustrated in FIG. 14 and thereby place the heater means 25B acrossthe leads L1 and 27B as indicated by heavy lines in FIG. 14 so that theheater means 25B will be operating. However, when the temperature outputeffect of the operating heater means 25B reaches the temperature of thetemperature setting of the control shaft 41B, the temperature responsivedevice 49B moves the movable switch blade 42B to an open conditionthereof whereby the switch 38B is open as illustrated in FIG. 15 toterminate the operation of the heater means 25B even though theindicating "on" bulb remains energized as illustrated.

Thus, the switch 38B is cycled on and off to tend to maintain thetemperature output effect of the heater means 25B at the particular "on"setting of the control shaft 41B for the reasons previously set forthand the indicator lamp 101 continuously indicates that the control shaft41B is in an "on" setting thereof.

Should the operator turn the control shaft 41B to the "off" condition ofFIGS. 12 and 13, such operation of the shaft 41B through the temperatureresponsive device 49B holds the switch blade 49B in the open conditionillustrated in FIGS. 12 and 13 so that the switch 37B remains in an opencondition thereof and thereby breaks the connection of the power sourceleads L1 to the indicating "on" light 101 so that the light 101 willnever be on during the entire time that the control shaft 41B is in the"off" condition thereof.

However, when the control shaft 41B is in the "off" condition thereof,should the output temperature effect 25B of the heater means 25B beabove the previously described safe value, the temperature responsivedevice 49B will, through the switch blade 42B, cause the switch blade43B to move against the adjustable contact 100 of the switch 39B toclose the switch 39B and thereby complete an electrical circuit from thepower source lead 101 through the closed switch 39B and the warningindicator 31B to cause the indicator 31B to indicate an unsafe outputtemperature effect of the heater means 25B as illustrated by heavy linesin FIG. 13.

Subsequently, when the output temperature effect of the heater means 25Bfalls below the unsafe value thereof, the temperature responsive device49B permits the switchblade means 42B and 43B to move from the positionillustrated in FIG. 13 to the position illustrated in FIG. 12 andthereby open the switch 39B and disconnect the power source lead L1 fromthe indicating lamp 31B.

Therefore, it can be seen that this invention not only provides improvedcontrol systems and methods of making the same, but also this inventionprovides improved control devices for such systems or the like.

While the forms and methods of this invention as now preferred have beenillustrated and described as required by the Patent Statute, it is to beunderstood that other forms and method steps can be utilized and stillcome within the scope of the appended claims.

What is claimed is:
 1. A control system comprising a source of energymeans, heater means, indicator means, and thermostatically operatedcontrol means having selector means for setting said control means in aheater means non-temperature producing "off" setting or in a heatermeans temperature producing "on" setting, said control means having asingle temperature responsive device operatively interconnected to saidmeans to interconnect said heater means to said energy means when theoutput temperature effect of said heater means is below a predetermined"on" setting of said control means and to disconnect said heater meansfrom said energy means when the output temperature effect of said heatermeans is above said predetermined "on" setting of said control means,said single temperature responsive device of said control meansoperating said indicating means to indicate that the output temperatureeffect of said heater means is above a certain value only when saidcontrol means is in said "off" setting thereof, said control meanshaving switch means continuously operating said indicating meansindependently of said temperature responsive device and regardless ofthe output temperature effect of said heater means to indicate that saidselector means is set in said "on" setting thereof only when saidselector means is set in said "on" setting thereof.
 2. A control systemas set forth in claim 1 wherein said indicating means comprises a firstindicator and a second indicator, said first indicator being operated bysaid temperature responsive device, said second indicator being operatedby said switch means.
 3. A control system as set forth in claim 2wherein said source of energy means comprises a source of electricalpower, said heater means comprises an electrically operated heatermeans, and said first and second indicators comprise first and secondlight bulbs.
 4. A control system as set forth in claim 3 wherein saidswitch means interconnects said source of power to said second bulb whensaid selector means is set in said "on" setting thereof.
 5. A controlsystem as set forth in claim 4 wherein said control means includes asecond switch means and a third switch means, said second switch meansbeing operatively associated with said temperature responsive device tointerconnect said power source to said first bulb only when saidselector means is set in said "off" setting thereof and said outputtemperature effect of said heater means is above said certain value,said third switch means being operatively associated with saidtemperature responsive device to interconnect said power source to saidheater means only when said selector means is set in said "on" settingthereof and said output temperature effect of said heater means is belowsaid predetermined "on" setting of said control means.
 6. A method ofmaking a control system comprising the steps of providing a source ofenergy means, providing a heater means, providing indicator means,interconnecting a thermostatically operated control means to said meansso as to cause a single temperature responsive device of said controlmeans to interconnect said heater means to said energy means when theoutput temperature effect of said heater means is below a predetermined"on" temperature producing setting of said control means and todisconnect said heater means from said energy means when the outputtemperature effect of said heater means is above said predetermined "on"temperature producing setting of said control means, causing said singletemperature responsive device of said control means to operate saidindicating means to indicate that the output temperature effect of saidheater means is in an "off" non-temperature producing setting thereof,and causing switch means of said control means to operate saidindicating means independently of said temperature responsive device andregardless of the output temperature effect of said heater means toindicate that said selector means is set in said "on" setting thereofonly when said selector means is set in said "on" setting thereof.
 7. Amethod as set forth in claim 6 and including the steps of forming saidindicating means from a first indicator and a second indicator, causingsaid first indicator to be operated by said temperature responsivedevice, and causing said second indicator to be operated by said switchmeans.
 8. A method as set forth in claim 7 wherein said source of energymeans comprises a source of electrical power and said heater meanscomprises an electrically operated heater means, and including the stepof forming said first and second indicators respectively from first andsecond light bulbs.
 9. A method as set forth in claim 8 and includingthe step of interconnecting said source of power to said second bulbwith said switch means when said selector means is set in said "on"setting thereof.
 10. A method as set forth in claim 9 and including thesteps of forming said control means to include a second switch means anda third switch means, operatively associating said second switch meanswith said temperature responsive device to interconnect said powersource to said first bulb only when said selector means is set in said"off" setting thereof and said output temperature effect of said heatermeans is above said certain value, and operatively associating saidthird switch means with said temperature responsive device tointerconnect said power source to said heater means only when saidselector means is set in said "on" setting thereof and said outputtemperature effect of said heater means is below said predetermined "on"setting of said control means.
 11. A control device for a system havinga source of energy means, heater means, and indicator means, saidcontrol device having thermostatically operated control means, saidcontrol device having a selector means for setting said control means ina heater means non-temperature producing "off" setting or in a heatermeans temperature producing "on" setting, said control means beingprovided with a single temperature responsive device for operativelyinterconnecting to said means to interconnect said heater means to saidenergy means when the output temperature effect of said heater means isbelow a predetermined "on" setting of said control means and todisconnect said heater means from said energy means when the outputtemperature effect of said heater means is above said predetermined "on"setting of said control means, said single temperature responsive deviceof said control means being adapted to operate said indicating means toindicate that the output temperature effect of said heater means isabove a certain value only when said control means is in said "off"setting thereof, said control device having switch means adapted tooperate said indicating means independently of said temperatureresponsive device and regardless of the output temperature effect ofsaid heater means to indicate that said selector means is set in said"on" setting thereof only when said selector means is set in said "on"setting thereof.
 12. A control device as set forth in claim 11 whereinsaid indicating means comprises a first indicator and a secondindicator, said first indicator being adapted to be operated by saidtemperature responsive device, said second indicator being adapted to beoperated by said switch means.
 13. A control device as set forth inclaim 12 wherein said source of energy means comprises a source ofelectrical power, said heater means comprises an electrically operatedheater means, and said first and second indicators comprise first andsecond light bulbs.
 14. A control device as set forth in claim 13wherein said switch means is adapted to interconnect said source ofpower to said second bulb when said selector means is set in said "on"setting thereof.
 15. A control device as set forth in claim 14 whereinsaid control means includes a second switch means and a third switchmeans, said second switch means being operatively associated with saidtemperature responsive device so as to be adapted to interconnect saidpower source to said first bulb only when said selector means is set insaid "off" setting thereof and said output temperature effect of saidheater means is above said certain value, said third switch means beingoperatively associated with said temperature responsive device so as tobe adapted to interconnect said power source to said heater means onlywhen said selector means is set in said "on" setting thereof and saidoutput temperature effect of said heater means is below saidpredetermined "on" setting of said control means.